Pulp molding apparatus



June 17,1941.

A. KEIDING PULP MOLDING APPARATUS FiIed July 8, 1937 2' Sheets-Sheet l Jgg- Jr ze Q Z6 2 e i O I .59 7 v ATTORNEYS June 17, 1941. A. KEIDING PULP MOLDING APPARATUS 2 Sheet s 2 iled July 8 TbR' v RNEYS Patented June 17, 1941 BEST AVAILABLE cop PULP MOLDING APPARATUS Andrew Keiding, Milwaukee, Wis, assignor to American Lace Paper Company, Milwaukee, Wis., a corporation of Wisconsin Application July 8, l937,-S'erial No. 152,512

9 Claims. (Cl. 92-54) This invention relates to improvements in pulp molding apparatus. The present application is a companion to my application Serial'No. 152,511,

filed July 8, 1937, which disclosed some of the features ofthe mold and its mode of operation and claimed a process in which this mold and apparatus may be used. Broadly it is the object of the invention to provide novel and improved molding apparatus having various features calculated to produce speedily and economically a more satisfactory molded product.

Specifically, the objects of the invention include the provision of a novel arrangement of mold, vat, tray and die; the provision of im-' proved means for the control of these several parts; the provision of a mold and control apparatus operable with a minimumamount of air displacement under vacuum or pressure; the provision of a mold in which a substantially uniform deposit of pulp is assured; the provision of a novel organization for assembly of the mold parts; andthe provision of an arrangement as-.

suring pulp deposits on the mold to a predeter mined dimension and uniform density without danger of loss of any of such deposits during larged scale showing the preliminary forming die used in the apparatus of Fig. 1.

Like parts are identified by the same reference characters throughout the several views.

The frame of the molding apparatus as dia grammatically illustrated includes a base 4, a column 5, and a back plate 6 uponwhich the cam shaft 1 is mounted. The column 5 provides a support for the pulp vat 8 which may be of any desired size or shape and supplied in any a usual or desired manner with pulp in'a mixture with water or other suitable vehicle.

A vertical guideway is provided at 9 in the column 5 for the slide lowhich carries by means of arm II, the mold generically designated by reference character I5 and hereinafter to be described in detail. The slide ID has a range of movement suflicient to permit the bodily immer- I,

sion of mold I5 in vat. 8 as indicated by the dotted lines.

Between the upper position of the mold I5 in v which it is illustrated in full lines in Fig. 1, and the lower dotted-line position thereof, there are two horizontal guideways hand I! upon which are respectively reciprocable the preliminary forming die assembly I and the discharge tray I8. The forming die assembly and tray are movable between positions in registry with mold I5 and retracted positions sufliciently remote from the path of the mold to offer no interference therewith.

There is an air connection through duct I9 at least part of which, as shown at 20, constitutes a flexible hose, by means of which either air or vacuum may be applied to the mold. The' duct I9 should desirably be as short as possible, and has only been illustrated at the indicatedlength for convenience of disclosure. The duct I9 connects with the air valve 2| in the pressure line 22 and the valve 23 in the vacuum line 24, it being understood that pipes 22 and 24 are connected with sources of pressure and partial vacuum in the ordinary manner.

" Before describing the structure of the mold and preliminary forming die in detail, a brief description will be given of the sequence of operations as controlled by the several cams mounted on shaft 1.

The slide III descends by its own weight. If such weight is insufi'icient to furnish the required pressure for certain operations a spring may be used to urge it downwardly. It is lifted by the lever 25 pivoted at 26 to the back plate 6 and having a slotted pivotal connection at 21 with the top of the slide. Intermediate its ends this lever carries a cam follower roller 28 acted onby the large cam 30, the length of the lever beyond the roller serving to multiply the motion 7 through the desired range of operation.

The tray I8 is connected by link 3| with lever 32, the cam follower roller 33 of which is-acted upon by cam 35. In similar manner the preliminary forming die I60 is connected by link '36 with lever 31, the cam follower roller 38 of which is acted upon by cam 40.- 1

The stem M of the air pressure jvalve 2| is controlled by cam 42. Similarlyfifihe'stem 43 of vacuum va1ve'23 is controlled bypam 44-. The

valves will be ,understood to contain springs maintaining them normally closed, this constructlon not being illustrated because it is conventional. The cam follower levers 33 and 38 are held to the peripheries of earns 35 and 40 respectively by the tension springs 65 and 46.

Figure 1 illustrates the parts just prior to the completion of one cycle and prior to the commencement of the next. The earns 35 and 40 are pushing aside the tray l8 and preliminary forming die I68. In the. tray is the damp molded blank M30 formed by the previous operation.

During the continued clockwise rotation of shaft '5 the retraction of the tray and forming die will be continued until the high points of cams 35 and as reach the cam followers 33 and 38, at which time the path of the mold 15 will be clear.

As the large cam 3d revolves beneath the cam follower roller 28', the roller .will reach the peripheral portion ii of the cam 38, whereby the slide it and mold i will be lowered into the pulp :bath in tank 8. The portion 68 of the cam surface is preferably of uniform radiusto provide a dwell after the mold enters the pulp.- The solids displaced by the entrance of the mold will re-collect about the mold and will tend to form on the surface thereof even' before the vacuum is applied by means of the operation of cam M on valve stem 53.

From the point designated by reference character 49 on the periphery of cam 3G to the point designated by reference character 56 a series of minor undulations will cause the" mold 85 to be reciprocated slowly up and down in the pulp during the continued application of vacuum .to the interior of the mold. It will be understood that this movement is typical of other movements which may be given to the mold within the pulp but the vertical reciprocation is preferred.

From the point W on the periphery of cam 30 to the point 5! thereof the mold is being retracted toward the full line position in which it is illustrated in Fig. 1. During the dwell represented by the space between points 5| and 52 on the periphery of cam 30, the cam 50 is reduced in radius at ,53 to control the advance of the preforming die H60 to a position beneath the mold I5 and in registry therewith.

Between point 52 and point 56 of cam 30 the mold is being lowered to press the uniform pulp in the preforming die. There is now a prolonged dwell to point 55 on cam 30 and throughout this period the pulp remains under pressure in the 5E5 to point 5'! the tray I8 is inserted. From 5? to 58 the mold is lowered somewhat into the tray, and at this point the nose of cam 42 engages air valve 4| (the vacuum valve 23 now being closed) to discharge a blast of air through pipe I9 into the mold to blow off the pulp blank I80 into the tray.

Between points 58 and 59 of cam 30 the. mold is retracted to the full line position in which it is shown in Figs. 1, and cams 35 and 4B operate during the ensuing period to retract the tray and preliminary forming die in the manner shown in the drawings. The cycle has now been completed.

The mold may conveniently be assembled on a tube 60 to which I braze or weld the cylindrical boss 6!. The sleeve 62 carried by-arm- I I has a stem at 63 to which the hose 20 is connected. The. "sleeve 62 is slipped telescopically over the tube 60 to seat on washer 64 under presssure of a clamp nut 65 threaded to the upper end of the tube. The tube is apertured at 66 in registry with the stem 53. The upper end of the tube is closed by a plug 61.

Near its lower end the tube 60 carries a displacement body of the form generally indicated at W. The displacement body 70 is completely closed to seal its interior. It is welded or brazed at its lower end and its top to the tube. It is formed to provide a laterally projecting flange at 1! upon which the parts of the mold proper may conveniently be mounted.

The mold proper comprises the foraminous support "and a cover 13 of fine mesh screen cloth. These parts are shaped to the desired form of the molded pulp blank and are outw'ardly fianged at 14 and 75 respectively to fit beneath the flange H of the displacement body 10.

For the formation of the desired container with a flat or upwardly convex bottom, vl2 have found it desirable that the mold shall havea downwardly convex bottom. Accordingly the bottom of the foraminous mold element 5.2 and the corresponding bottom portion of the screen cloth cover 13 are both downwardly convex as clearly shown in Fig. 2.

The several flanges H, 74 and 75 may conveniently be clamped together. ring ibis held by screws '11 to the annulus E8, the latter being shouldered to provide a seat for flange 15 of the wire cloth cover. It is important to the invention that the annulus 18 shall have a substantially horizontal shoulder at 8i) and shall thence extend downwardly and outwardly at 8| to provide a recess well below the top of the foraminous element 12 and screen cloth 13 as a means'of sharply defining the upper limit of pulp deposit on the outside of the This entire hood may he slid upwardly on cylinscreen cloth. The form of the annulus 73 is such that when the mold is removed from the pulp bath any water dripping from the exterior of the annulus will fail. free of the deposit of pulp and will not tend to wash away any of the pulp which has been left on the screen cloth.

A hood or shroud at 83 is made in annular form with a sleeve portion 84 slidable on the cylinder 6| of tube 60. The lower 'margin of the hood comprises a generally cylindrical skirt at 85 which is sleeved over the ring I6 and engages in a shoulder portion of the annulus 18.

der 6| to expose the clamping screws 11.. When lowered to the position shown in Fig. 2 the hood finishes the mold and is frictionally held in place thereon.

The tube 60 is provided at its lower end with a closure 81 but communicates with the space between the foraminous mold element 12 and the displacement body 10 through a series of .apertures 88. The closure 81 comprises a disk ing-an even and uniform deposit of pulp over the entire exposed surface of the mold screen I3. Another important reason for the baflie is to protect the deposited pulp from deformation.

The clampingwhen air is. supplied under pressure through tube 60. g

In addition toassisting in the control of the deposit. on the mold, the displacement body I minimizes the volumetric capacity of the mold,

thus reducing the load on the vacuum pump' complementary to the formof the exposed screen cloth cover 13 of the mold. It has a downwardly convex bottom at 96, an imperforate side wall at 91, a radial flange 99 for mounting it upon the box 90, and an upwardly extending flange 99' having a beveled external surface I00 complementary to the surface 8| of the annulus 18 of the mold. The thickness of flange 99 is somewhat less than the width of shoulder 89 of the annulus 18 of the mold, the difference in radial dimension being just suflicient to accommodate the compressed pulp formed on the exposed surface of the mold screen 13. When the mold is lowered into the forming die assembly Hill, the

ment 95 rests directly on the bottom of the box 99 to sustain the pressure exerted by the mold.

Since it is only intended that the invention be illustrated diagrammatically, it will be underproper which is illustrated at 95 and'is fully 'tion thereof and connected marginally to said screen and elsewhere spaced therefrom, said displacement body having sides converging toward said wall portion and toward the marginal connection of the body with the screen, and a vacuum pipe extending through said displacement body and communicating with the space between .said displacement body and said screen adjacent weight of slide I0, augmented if necessary by I spring pressure or other suitable means, c0m-.

the bottom portion of said mold.

2. In a device for molding fibrous pulp, the combination with a cup-shaped mold having 'a screen constituting a bottom and aside wall portion, of a displacement body partially filling the portion of said mold within the wall portion thereof and connected marginally to said screen, i

said displacement body having sides converging toward said wall portion and toward the marginal connection of the body with the screen,

' the portion of said mold within the wall portion uniform compression of the pulp to its extreme upper margin.

For the most uniform results in deposit of pulp it is preferred to employ not merely the peculiar shaped displacement body 10 and the baiiie 81, but alsoto round convexly downwardly the bottom of the mold element 12 and screen 13. This eliminates any sharp angles between the bottom and the sides of the vessel to be formedon the mold. Where a sharp angle is present at the mold the pulp deposit at the corner is excessive and the felting of the pulp fibers will be such that in at least some of the products a capillary crack may be formed at the I corner, despite any subsequent treatment which to reverse its convexity. In any event, it is preferred that not merely the original deposit of l the pulp, but also the initial compression thereof,

shall take place in the convexly rounded form as shown.

'Iihe use of steam in the preforming inold ISO is by no means essential but it is preferred.

The heat on the exterior of the pulp blank, to-- gether with the pressure, drives the water inwardly and facilitates its removal by the vacuum screen adjacent the bottom portion of said mold,

thereof and connected marginally to said screen, said displacement body having sides converging toward said wall portion and toward the marginal connection of the body with the screen,

. and a vacuum pipe extending through said displacement body and communicating with the space between said displacement body and said together with baflle means interposed between the end of said vacuum pipe and the bottom portion of said screen, the bottom portion of said screen being convexly outwardly rounded.

4. In a device for molding fibrous pulp, the combination with a tubular support, of a displacement body mounted on said support and provided with a radially projecting flange, a cupshaped foraminous mold element enclosing said displacement body and having a complementary flange nested with respect to said first mentioned flange, a cup-shaped mold screen on said foraminous support having a complementary flange nested with respect to the first mentioned flanges,

and clamping means securing the several flanges in nested relation.

5. In a device for molding fibrous pulp, the combination with a tubular support, of a displacement body mounted on said support and provided with a radially projecting flange, a cupshaped foraminous mold element enclosing said within the mold. The base IOI on the die eledisplacement body and having a complementary with an external shoulder spaced from said screen. i

6. A device for molding fibrous pulp comprising the combination with a tubular support, of a'displacement body having aradially projecting flange and a downwardly tapering wall, a foraminous mold element of cup-shaped form encircling said displacement body and provided with a complementary flange, a screen fitted to said element and having a further complementary flange, said tubular support having baflle means providing controlled communication between said support and the space between said displacement body and said foraminous mold element, and means connecting the flanged portions-of said mold element and screen to the flange of said body.

7. A device for molding fibrous .pulp comprising the combination with a tubular support,

of a displacement body having a radially pro- Jecting flange and a downwardly tapering wall, a foraminous mold element of cup-shaped form encircling said displacement body and provided with a complementary flange, a screen fitted to saidselement and having a further complementary flange, said tubular support having baflle \means providing controlled communication between said support and thespace between said displacement body and said foraminous mold element, and means connecting the flanged portions of said mold element and screen to the flange of said body, said means comprising annular clamps, the lowermost of which engages the side of said screen materially below the top of the space between the displacement body and said element.

8. A device for molding fibrous pulp com-' prising the combination with a tubular support,

of a displacement body having a. radially projecting flange and a downwardly tapering wall, a foraminous mold element of cup-shaped form encircling said displacement body and provided with a complementary flange, a screen fitted to said element and having a further complementary flange, said tubular support having baflle means providing controlled communication between said support and the space between said displacement body and said foraminous mold element, and means connecting the flanged portions of said mold element and screen to the flange of said body, said means comprising annular clamps, the lowermost of which engages the side of saidscreen materially below the top of the spacebetween the displacement body and said element, said last mentioned clamp having a depending shoulder at a point spaced outwardly from said screen.

9. In a device for molding fibrous pulp, the

a combination with a perforate, contoured, hollow mold having a screen with, side and bottom walls, means closing thetop of the mold and including a displacement body depending within the mold and having a side wall spaced from and progressively approaching the side wall of the mold in an upward direction, whereby to progressively reduce the lateral clearance between the mold and the body toward the top of the mold, the bottom portion of said body being provided with an outlet communicating with the space between said body and said screen adjacent the bottom of said mold.

ANDREW KEIDING. 

